Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-09-25
Astronomy and Astrophysics
Astrophysics
44 pages, 4 figures, to appear in ApJ (vol. 552)
Scientific paper
10.1086/320561
We generalize the derivation of dynamo coefficient $\alpha$ of Field et al (1999) to include the following two aspects: first, the de-correlation times of velocity field and magnetic field are different; second, the magnetic Prandtl number can be arbitrary. We find that the contributions of velocity field and magnetic field to the $\alpha$ effect are not equal, but affected by their different statistical properties. In the limit of large kinetic Reynolds number and large magnetic Reynolds number, $\alpha$-coefficient may not be small if the de-correlation times of velocity field and magnetic field are shorter than the eddy turn-over time of the MHD turbulence. We also show that under certain circumstances, for example if the kinetic helicity and current helicity are comparable, $\alpha$ depends insensitively on magnetic Prandtl number, while if either the kinetic helicity or the current helicity is dominated by the other one, a different magnetic Prandtl number will significantly change the dynamo $\alpha$ effect.
No associations
LandOfFree
The Dependence of Dynamo $α$-Effect on Reynolds Numbers, Magnetic Prandtl Number, and the Statistics of MHD Turbulence does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Dependence of Dynamo $α$-Effect on Reynolds Numbers, Magnetic Prandtl Number, and the Statistics of MHD Turbulence, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Dependence of Dynamo $α$-Effect on Reynolds Numbers, Magnetic Prandtl Number, and the Statistics of MHD Turbulence will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-605365